Circuit breaker employing high and low intensity gas blast



July 22, 1952 G. E. JANssoN CIRCUIT BREAKER EMPLOYING HIGH AND Low INIENSIIY GAS BLAST Filed oct. s, 1949 ce \\o\\ 1 W//f/ /f 1/ Patented July 22, 1952 CIRCUIT BREAKERy EMPLOYING HIGH AND LOW INTENSITY GAS BLAST Gustav E. Jansson, North Quincy, Mass., assigner to AllisfChalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application Getober 3, 1949, Serial No. 119,373

1l. Claims.

This invention relates to circuit interrupting devices and more particularly to arc extinguishing means for use in connection therewith. Specically this invention is an improvement on the invention disclosed and claimed in George A. Burnhams application Serial No. 126,572, iiled November 10, 1949.

In the construction and operation of circuit interrupters, it is frequently necessary to provide means for extinguishing quickly the arc which is drawn between separable arcing contacts. This are is usually blown by blowout means, such as an air blast, into an arc chute which is arranged to quench the arc by lengthening it, cooling it, or otherwise.

The interrupting capacity of a circuit breaker interruptor in a high voltage circuit depends to a great extent on the circuit characteristics relating to the rate of increase of recovery voltage when the current is interrupted. Although the breaker may be successful in interrupting the current momentarily, the recovery voltage across the interrupting gap k,may rapidly rise to such a value that arcing is reestablished before the breaker rhas sumciently increased the dielectric strength of the gap. For interrupting higher currents under such conditions, it would be necessary to increase the pressure and the intensity of the gas blast. If it is impractical to increase the gas pressure, the size of the blast l passage or the type of gas passage or passages may be varied to provide for greater gas volume ory greater interrupting ability. Such changes, however, usually result in either a more expen-r sive or larger breaker.

AIn accordance withA theinvention claimed an arc chute is provided adjacent a pair of arcing contacts for receiving the arc at one end thereof and exhausting the arcing products at the other end thereof. The arc chute comp-rises a. viirst blast passage for interrupting relatively high currents and a second blast passage for interrupting relatively low currents. An insulating blast divider may be arranged between the source of iluid under pressure and the arc chute of the circuit breaker for distributing the blast from the point where it arrives in ,highly concentrated form to the arcing zones. This blast divider may comprise a pair of passages or nozzles which diverge from the point where the blast arrives toward the two spaced arcing zones at the upstream ends of the arc chute passages. The nozzles of the blast divider are so arranged to divide the blast of gas into a high intensity stream which news through the rst blast passage for interrupting high currents and a low intensity stream which iiows through the second blast passage for interrupting lower currents. By inserting a suitable resistor in the circuit by means of the arc in the iirst blast passage, the voltage recovery rate of the circuit is decreased, and if the circuit is not interrupted by the high intensity blast, it may be interrupted at a greatly decreased current at a much more favorable re-` covery rate by the comparatively limited blast of the low intensity stream in the second blast passage. In this manner, the interrupting capacity of the circuit breaker for a given blast pressure and gas consumption is greatly increased.

It is, therefore, one object of the present invention to provide a new and improved arc interrupting device.

Another object of the invention is to provide a new and improved arc extinguishing device for interrupting a plurality of arc currents.

A further object of this invention is to provide a plurality of blast passages for interrupting arc currents of varying magnitude.

`A still further object of this invention is to provide an improved fluid blast circuit interrupter which divides a blast of gas into a plurality of streams of different intensities, the stream of highest intensity flowing through a passage for interrupting a current of high magnitude and ea-ch stream of progressively smaller intensity iiowing through a different passage for interrupting a current of progressively smaller magnitude.

Objects and advantages other than those above set yforth will be apparent from the following description when read in connection with the accompanying drawings in which:

Fig. 1 is a diagrammatic showing partlyy in cross section of a iiuid blast circuit breaker embodying the present invention; n

Fig. 2 is a view in cross section of the embodiment illustrated in Fig. 1 taken along the line II-II; and

Fig. 3 is a cross sectional View of the embodiment illustrated in Fig. 1 taken along the line IIL-III.

The cross blast type air blast circuit breaker show-n by way of example in Fig. 1 comprises relatively movable ar'clng contacts, such as fixed contact structure l of the linger type and a pivoted`bladelike contact 8. The fixed contact structure may comprise a plurality of current carrying contacts and an arcing contact as is well known, and is electrically connected to one line terminal 9 of the breaker. The blade-like movable contact is connected to the other line termian actuating mechanism (not shown) through a connecting rod I I for operating the movable contact between closed and open circuit positions.

For the purpose of extinguishing the arc formed between the contacts when a power circuit connected thereto is opened, an insulating arc extinguishing structure I2 is arranged with respect to the contacts so that the arc is drawn at the entrance of the structure directly opposite a gas blast supply conduit I3. The conduit I3 is suitably connected through a blast valve (not shown) to a source of compressed gas, such as air, comprising for example a storage tank and compressor equipment (not shown).

The arc extinguishing structure may, for example, define a double barrel arc chute I4 comprising a rst blast passage I5 for interrupting relatively high currents and a second blast passage IG arranged parallel with and spaced apart from passage I5 for interrupting relatively low currents. The blast passages I5 and I6 as illustrated in Fig. 3 have substantially uniform cross sections which may be rectangular or circular in form.

An insulating blast divider I9 may be arranged between the gas supply conduit I3 and the arc chute I4 for distributing the blast from the point Where it arrives in highly concentrated form by the narrow blast supply conduit I3 to an arc chamber provided for enclosing the arcupon inception thereof. The arc chamber comprises arcing zones 2) and 2I which are spaced apart and situated at the upstream end of the double barrel arc chute I4. The blast divider comprises a pair of passages forming nozzles 22 and 23 which diverge from the point where the blast arrives in highly concentrated form toward the two spaced arcing zones and 2| at the upstream ends of the chute passages I5 and I5. Nozzle 22 directs the blast therethrough in a direction substantially at right angle to the path of movement of contact 8 across the nozzle. The gas blast supply conduit I3 is preferably of a relatively small cross sectional area and is arranged substantially coaxially with respect to the rst blast passage I5 and hence substantially out of alignment relative to the second blast passage I6. The blast divider is arranged intermediate the arc extinguishing structure I2 and the blast supply conduit I3 and may extend into the upstream end of arc chute I4. The walls of the blast divider I9, asillustrated in Fig. 2, deiine a passage 24 therethrough which accommodates the movable sickle-shaped blade contact 8. These walls closely surround contact 8 and control the escape of compressed air and arc products through passage 24 into blast passages I5 and I6. f

A pair of probe electrodes 25 and 25 may be mountedwithin the arc extinguishing structure I2 for aiding arc extinguishment. Probe electrode 25 is mounted within arc chute I4 and particularly blast passage I5 and probe electrode 2S is mounted within blast passage I5. In order to lower the value of the arc current at a predetermined time during arc extinguishment, a cur- 4 rent limiting resistor 21 interconnects probe elec; trode 25 and the multiple finger contacts of the iixed contact structure 'I.

The circuit breaker illustrated in the drawing is shown with the cooperating arcing contacts in the closed circuit position. An opening operation is initiated by admission of gas under pressure to supply conduit I3. The further flow of such gas through passage 24 is at iirst impeded by contact 8, which obstructs the passage. Actuation of the connecting rod II moves blade contact 8 toward the right to open the electric circuit.

As the blade contact 8 is separated from the fixed contact 'I an arc is drawn across the arcing zone 20 leading to the first blast passage I5 and substantially concurrently therewith a path is opened for blast of gas of high intensity through the supply conduit I3 and nozzle 22 of blast divider I9 to the first blast passage I5 transversely to the gap formed by contacts 1, 8 upon separation thereof. This blast includes substantially all the gas being supplied through conduit I3, and drives or loops the arc from zone 20 into passage I5. Frequently the arc is interrupted in the first blast passage by the blast of gas flowing through nozzle 22. As the blade continues to move toward the right, the arc is extended into zone 2| if it is not already extinguished. The second blast passage I6 and nozzle 23 of blast divider I9 are uncovered and part of the arc is driven or looped from zone 2I into blast passage I5 by the blast from nozzle 23.

In accordance with the invention the supply conduit I3 and the blast passage I5 of arc chute I4 are substantially coaxially aligned. The momentum of the gas blast therefore tends to maintain the blast in its original vertical direction. thereby causing a concentration of the blast of gas under pressure upon the stationary iinger contacts and the iirst blast passage I5 even after nozzle 23 is unsealed by contact 8. This concentration of the blast in the form of a high intensity stream on the stationary arcing contact structure 'I causes an intense deionization of the arc path at the point where an electrical breakdown is most likely to occur. The concentration of the blast upon arcing zone 20 and the first blast passage I5 causes a rapid rise of the resistance of the portion of the arc situated at the upstream end of the blast passage I5. The arc rises and comes in contact with probe electrode 25. The section of the arc which is shunted by resistor 21 interconnecting the fixed finger contact structure 'I with the proble electrode 25 arranged in the first blast passage I5 Will be rapidly extinguished and replaced after the first current zero by current through the resistor 21 From then lon in the interrupting cycle, the task is limited to interrupting a resistor limited arc current of lower intensity and this may be achieved either at the upstream end of blast passage I5 or at the upstream ends of the iirst and second blast passages I5 and I5. respectively.

The intensity of the blast of gas necessary to interrupt a resistor limited current of low inltensity is much lower than that necessary tointerrupt a higherarc current. Therefore, a blast of gas of relatively low intensity is provided through blast passage IE for interrupting lower currents. The lower intensity of such blastresults both from the division of the blast into two streams through nozzles 22 and 23 and ofthe arrangement of nozzle 23 vout of axial 'relation with supply conduit I3. whereby the momentum of `the blast forces it to flowk principally through nozzle 22. If the arc is not interrupted in blast passage l5by the high intensity stream provided by nozzle 22 of blast divider I9 the resistor limited current is then interrupted in blast passage I8 by a lower intensity blast of gas provided by nozzle 23. yAlthough but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that variouschanges and modiiications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

` It is claimed and desired to secure by Letters Patent: Y

l. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, means for supplying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chute mounted adjacent said contacts for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a first blast passage for interrupting relatively high currents and aseccnd blast 4passage forinterrupting relatively low currents, and means extending from a point upstream of said contacts toward said arc chute for dividing the blast into a high intensity stream and a low intensity stream, said high intensity stream ilowing through said first blast passage and said low intensity stream iloiving through said second blast passage.

2. In a fluid blast circuit interrupter, the combination comprising: a source of iluid under pressure, separable arcing contacts for establishing anardmeans for supplying a blast oi fluid from said source substantially at right angle to the path of contact movement whereby the blast -is directed transversely to the arc gap formed between the contacts upon separation thereof, an are chute `mounted adjacentsaid contacts for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a ilrst blast passage for interrupting relatively high currents and a second blast passage for interrupting relatively low currents, and means extending from a point upstream of saidcontacts toward said arc chute for dividing the blast intofa high intensity stream and a low intensity stream, said high intensity stream flowing through said ilrst blast passage and said low intensity stream ilowing through said second blast passage.

3. In a fluid blast circuit interrupter, the combination comprising: a source of iluid under pressure, separable arcing contacts for establishing an arc, v.a conduit for conveying a blast of fluid from" said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chute mounted adjacent said contacts for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a first blast passage substantially axially aligned with said conduit for interrupting relatively high currents and a second blast passage mounted substantially out of alignment with said conduit for interrupting relatively low currents, and means extending from a point upstream of said contacts to a point downstream of said contacts for dividing the blast into a high intensity stream and a low intensity stream, said high intensity stream flowing through said ilrst blast passage and said low intensity stream flowing through said second blast passage. f

e. In a fluid blast circuit interrupter, the combination comprising: a source of iluid under pressure, separable arcing contacts for establishing an arc. a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chute mounted adjacent said contacts for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising aiirst blast passage substantially axially aligned with ,said conduit for interrupting relatively highcurrents and a second blast passage mounted substantially out of alignment with said conduit kfor interrupting relatively low currents, and a blast divider mounted between said conduit and said arc chute for dividing the blast into a high intensity stream and a low intensity stream, said high'intensity stream flowing through said rst blast passage and said ,low intensity stream ilowing through said second blast passage. 1

5. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, a conduit for conveying a blast of uid from said source adjacent said contacts for extinguishing the are drawn upon separation of said contacts, an arc chute for receiving Athe arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a first blast passage mounted adjacent said contacts and substantially axially aligned with said conduit for interrupting relatively high currents and a second blast passage mounted parallel with said first blast passage but substantially out of alignment with said conduit for interrupting relatively low currents, and a blast divider Imounted between said conduit and said'arc chute for dividing the blast into a high intensity stream and aflow intensity stream, said `high intensity stream lowing through said first blast passage and said low intensity stream ilowing through said second blast passage.

6. In a iluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, aconduit for .conveying a blast of iluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said are chute comprising viirst blast passage and a second blast passage, `an arc chamber mounted between said conduit and said arc chute for enclosing the arc upon inception thereof, anda blast divider mounted within said chamber and extending from a point upstream of said contacts toward said arc chute and vforming with said chamber a pair of nozzles, one of said nozzles directing a high intensity stream of iluid under pressure into said first blast passage for interrupting relatively high currents and the other of said nozzles directing a lower intensity stream of fluid under pressure into said second blast passage for interrupting relatively low currents.

'7. In a iluid blast circuit interrupter, the combination comprising: a source of iluid under pressure, separable arcing contacts for establishing an arc, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a first blast passage and a second blast passage, an arc chamber mounted between said conduit and said arc chute for enclosing the arc upon inception thereof, and a blast divider extending from a point upstream of said contacts to a point downstream of said contacts and forming with said chamber a pair of nozzles for directing a high intensity stream of fluid and a low intensity stream of fluid into said arc chute, one of said nozzles substantially axially aligned with said conduit for directing said high intensity stream into said first blast passage for interrupting relatively high currents and the other of said nozzles directing said low intensity stream into said second blast passage for interrupting relatively low currents.

8. In a iiuid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, a means for providing a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chute for receiving the arc at one end thereof, said arc chute comprising a plurality of blast passages, each passage interrupting a current of a different magnitude, and means extending from a point upstream of said contacts to said arc chute for dividing the blast into a plurality of streams of different intensities, the stream of highest intensity iiowing through the passage for interrupting the current of highest magnitude and each stream of progressively smaller intensity flowing through the passage for interrupting a current of progressively smaller magnitude.

9. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, contact means comprising stationary multiple finger contacts and a cooperating movable blade Contact for establishing an arc, means for supplying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chute mounted adjacent saidcontacts for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a first blast passage for interrupting relatively high currents and a second blast passage for interrupting relatively low currents, and blast divider means extending from a point upstream of said contacts toward said arc chute for dividing the blast into a high intensity stream and a low intensity stream, said high intensity stream fiowing through said first blast passage and said low intensity stream flowing through said second blast passage, said movable blade contact effectively sealing said second blast passage until said contacts have separated a predetermined distance.

10. In a fluid blast circuit interrupter, the combination comprising: a source of fiuid under pressure, contact means comprising stationary multiple nger contacts and a cooperating movable blade contact for establishing an arc, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a first blast passage for interrupting relatively high currents and a second blast passage for interrupting relatively low currents, a blast tube of relatively small cross sectional area substantially coaxially aligned with said first blast passage and substantially out of alignment relative to said second blast passage for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chamber mounted between said blast tube and said arc chute for enclosing said arcing contacts, and a blast divider mounted within said chamber and forming with said chamber a pair of nozzles which diverge from the downstream end of said blast tube toward the blast passage of said arc chute. one of said nozzles directing a high intensity stream of fluid into said first blast passage and the other of said nozzles directing a lower intensity stream of iiuid into said second blast passage.

l1. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, contact means comprising stationary multiple finger contacts and a cooperating movable blade contact for establishing an arc, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end. said arc chute comprising a first blast passage for interrupting relatively high currents and a second blast passage for interrupting relatively low currents, a blast tube of relatively small cross sectional area substantially coaxially aligned with said first blast passage and substantially out of alignment relative to said second blast passage for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc chamber mounted between said blast tube and said arc chute for enclosing said arcing contacts, and a blast divider mounted within said chamber and forming with said chamber a pair of nozzles which diverge from the downstream end of said blast tube toward the blast passages of said arc chute, one of said nozzles upon separation of said arcing contacts directs a high intensity stream of fluid into said first blast passage and the other of said nozzles upon a predetermined movement of said blade contact directs a lower intensity stream of iiuid into said second blast passage.

GUSTAV E. J ANSSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,290,708 Rankin July 21, 1942 2,306,240 Wyman Dec. 22, 1942 2,345,375 Bennett Mar. 28, 1944 2,347,052 Hobson Apr. 18, 1944 

